Week 6 // The Endocrine System Flashcards
nervous system releases
neurotransmitters
endocrine system releases
hormones
After they are released, most hormones. go to….
blood.
They circulate through the blood and bind to receptors on “target cells”
Which is closer to the site of release? Hormones or neurotransmitters?
Neurotransmitters are released close to the site of release. Hormones are farther away.
time to onset of action (NT vs Hormones)
NT
Typically within milliseconds (thousandths of a second).
HORMONES
Seconds to hours or days.
duration of action (NT vs Hormones)
Duration of action NT Generally briefer (milliseconds). Hormones Generally longer (seconds to days).
Types of target cells NT vs. Hormones
Types of target cells
Muscle (smooth, cardiac, and skeletal) fibers, gland cells, other neurons.
Cells throughout body.
Exocrine glands secrete their products where? * pay attention
secrete their products into ducts
> None of these are hormones!
> Exocrine glands include sudoriferous (sweat) glands, sebaceous (oil) glands, mucous glands, digestive glands and several others throughout the body
Exocrine glands secrete their products where? * pay attention
secrete their products into ducts
> None of these are hormones!
> Exocrine glands include sudoriferous (sweat) glands, sebaceous (oil) glands, mucous glands, digestive glands and several others throughout the body
Do endocrine glands have ducts?
Endocrine glands do not have ducts; instead they secrete their hormones directly into the interstitial fluid* that surrounds them
interstitial fluid*
fluid that surrounds the cells
Where does the endocrine gland secrete the hormone?
The hormones diffuse into the blood stream through capillaries and are carried to target cells throughout the body
Endocrine glands include the pituitary, thyroid, parathyroid, adrenal and pineal glands
Where does the endocrine gland secrete the hormone?
The hormones diffuse into the blood stream through capillaries and are carried to target cells throughout the body
Endocrine glands include *
the pituitary, thyroid, parathyroid, adrenal and pineal glands
Exocrine glands include *
sudoriferous (sweat) glands, sebaceous (oil) glands, mucous glands, digestive glands and several others throughout the body
Certain organs and tissues that are not part of the endocrine system also secrete hormones because they contain secreting cells. What are they?
Secreting cells can be found in the (hypothalamus, thymus,) pancreas, ovaries, testes, kidneys, stomach, liver, small intestine, skin, heart, adipose tissue and placenta
heart
the encdorcrine together with t he nervous system, maintain homeo. It regulates the
homostasis
Target cells
Hormones traveling throughout the body will only affect target cells that possess specific protein receptors for the hormone
Receptors are continually being synthesized and broken down
Receptors may be down-regulated in the presence of high concentrations of hormone
Receptors may be up-regulated in the presence of low concentrations of hormone
how can hormones only work on target cells?
Specific protein receptors for hormones
How do receptors change over time?
They are continually synthesized and broken down.
- Receptors may be down-regulated in the presence of high concentrations of hormone
- Receptors may be up-regulated in the presence of low concentrations of hormone
Local hormones that don’t circulate are called
paracrine
Hormones that work on the same cell that secretes them are called
autocrine.
Hormones solvability *
Hormones are either lipid-soluble or water soluble
Which hormones are lipid soluble? *
(steroid hormones, thyroid hormones, nitric oxide) or water-soluble (amine hormones, peptide and protein hormones, eicosanoid hormones
Which hormones are water soluble? *
Water-soluble hormones circulate freely in the plasma
Lipid-soluble hormones circulate bound to transport proteins
What is plasma?
Liquid inside the blood.
How is hormone secretion controlled? *
Hormones are secreted in short bursts when needed
Secretion is regulated by:
- Signals from the nervous system
- Chemical changes in the blood
- Other hormones
Most hormone regulation is achieved via negative or positive feedback?
Most hormone regulation is achieved via negative feedback
Only a few hormones operate via positive feedback.
These two glands work together to control other endocrine glands
hypothalamus and pituitary gland
Anterior lobe of pituitary makes up _____ % of weight of pituitary gland
The anterior lobe (adenohypophysis) makes up 75% of the weight of the pituitary gland
Anterior lobe secretes ____ hormones
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The posterior lobe (neurohypophysis) is made of _______ and releases____ hormones made by the hypothalamus
The posterior lobe (neurohypophysis) is made of neural tissue and releases two hormones made by the hypothalamus
Hypothalamus controls the pituitary gland secretion this way.
The hypothalamus secretes releasing and inhibiting hormones that control the release of hormones by the pituitary gland
They reach the pituitary gland via the hypophyseal portal system
Most plentiful hormone in anterior pituitary gland is this:
Human growth hormone (hGH) is the most plentiful anterior pituitary hormone
hGH is released this often
It is released in bursts every few hours by somatotrophs
Their activity is controlled by two hypothalamic hormones: growth hormone-releasing hormone (GHRH) and growth hormone-inhibiting hormone (GHIH)
Hormones of the anterior pituitary gland (no need to study)
In summary, the anterior pituitary gland secretes: Human growth hormone (hGH) Thyroid-stimulating hormone (TSH) Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Prolactin (PRL) Adrenocorticotropic hormone (ACTH) Melanocyte-stimulating hormone (MSH)
Does the posterior pituitary synthesize hormones?
No.
The posterior pituitary gland does not synthesize any hormones, but stores and releases from axon terminals two hormones produced by the neurosecretory cells of the hypothalamus: Oxytocin (OT) Antidiuretic hormone (ADH)
ADH Antidiuretic hormone (major function)
more or less urine (More ADH, less urine)
ADH decreases urine output as part of a negative feedback loop where osmoreceptors in the hypothalamus monitor blood osmotic pressure
An increase in blood volume causes a decrease in ADH secretion
A decrease in blood volume causes an increase in ADH secretion
Oxytocin (major function)
Oxytocin is released in response to stretch placed on the cervix during childbirth.
Oxytocin affects the:
Mother’s uterus – enhances contractions
Mother’s breasts – stimulates milk ejection by the mammary glands in response to suckling
Thyroid Gland
The thyroid gland is a butterfly-shaped gland located inferior to the larynx and anterior to the trachea
It has right and left lateral lobes connected by an isthmus
Some glands also have a pyramidal lobe projecting from the isthmus
Thyroid hormones
Follicular cells are stimulated by TSH to produce T4 and T3
Parafollicular cells produce the hormone Calcitonin to help regulate calcium homeostasis
Function of Thyroid hormones
Increase basal metabolic rate (BMR)
Help maintain normal body temperature
Stimulate protein synthesis
Increase the use of glucose and fatty acids for ATP production
Upregulate beta (β) receptors that attach to catecholamines
Work with hGH and insulin to accelerate body growth
Parathyroid hormone major function
Stimulates release of calcium by bones into the bloodstream, Absorption of calcium from food by the intestines, Conservation of calcium by the kidneys.
calcitonin
Calcitonin is involved in helping to regulate levels of calcium and phosphate in the blood, opposing the action of parathyroid hormone.
Suprarenal Glands
Secretes
- mineralocorticoids: used to regulate mineral homeostasis Aldosterone is the major mineralocorticoid secreted by the adrenal gland. It helps regulate sodium and potassium homeostasis
- glucocorticoids that affect glucose homeostasis
- weak androgens
Suprarenal glands glucocorticoid function:
They help control: Protein breakdown Glucose formation Lipolysis Resistance to stress Inflammation Immune responses
Androgen produced by Suprarenal Glands
DHEA
Almost no effect in males
Libido in women (converted to estrogens)
In menopausal women, all female estrogens come from adrenal androgens
Pancreatic Islets
Pancreatic islets are groups of cells in your pancreas. Islets contain several types of cells, including beta cells that make the hormone insulin.
The pancreas is located in the curve of the duodenum
It is both an endocrine and exocrine gland
- caciitrol
Calcitriol* (active form of vitamin D)
Aids in absorption of dietary calcium and phosphorus.
*Synthesis begins in the skin, continues in the liver, and ends in the kidneys.
- Calcitriol
Calcitriol* (active form of vitamin D)
Aids in absorption of dietary calcium and phosphorus.
*Synthesis begins in the skin, continues in the liver, and ends in the kidneys.
Types of stress
Eustress is helpful, everyday stress that prepares us to meet challenges
Distress is any type of harmful stress that may be damaging
Stages of stress response
The fight-or-flight response (first stage of the stress response) stimulates the body’s resources to prepare for immediate activity
The resistance reaction is the second stage in the stress response and lasts longer than the fight-or-flight response
If this lasts too long, exhaustion will result
